Thread rolling tool

ABSTRACT

The present invention is directed to a cold roll tool that may be used in forming various threads. In one illustrative embodiment, the tool comprises a tool holder, a boring bar and a cold roll wheel operatively coupled to the boring bar, wherein a position of the cold roll wheel relative to the tool holder along a first direction is moveable. In another illustrative embodiment, the tool comprises a tool holder, a boring bar slidingly coupled to the tool holder to thereby allow movement of the boring bar in a first direction relative to the tool holder, and a cold roll wheel operatively coupled to the boring bar.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention is generally related to the field of threadformation, and, more particularly, to a thread rolling tool that may beemployed in forming threads on various components.

2. Description of the Related Art

Threaded connections are very commonplace for connecting variouscomponents to one another. For example, in the oilfield industry,sections of pipe or tubulars are sometimes connected to one another by athreaded connection, i.e., a box (female) threaded connection formed onone end of a pipe, and a pin (male) threaded connection formed on theother end of the pipe. Sections of pipe are coupled to one another bythese threaded connections. Of course, there are many other industriesand applications where threaded connections are routinely and widelyemployed.

There are a variety of well known manufacturing techniques for formingthreads on the various components. Moreover, the size, shape andconfiguration of the threads formed by such processes may vary widelydepending upon the particular application and the anticipated loadingconditions. In some cases, threads are formed by a process wherein acutting tool is employed to form the threads in the component, e.g., asection of pipe, using a lathe and known tooling components. Thereafter,in some cases, it is desirable that the mechanical properties of thethreads be enhanced by cold working the threads, i.e., it is desirableto enhance the mechanism properties of the root of the threads and thevarious thread surfaces where high stress points could result in fatiguefailure. By cold working the threads, various mechanical properties ofthe thread may be improved, e.g., hardness, etc. There are many toolsand techniques on the market for cold working threads. Most of suchthread rolling tools are designed to fit onto CNC machines and/or aredesigned for use with industry standard thread profiles, e.g., APIconnectors.

FIG. 1 provides a schematic example of at least one technique for coldworking threads formed on a component. As depicted therein, a pluralityof schematically depicted threads 10 are formed on a component 12. Acold roll wheel 14 having an end 16 is depicted positioned above thethreads 10. After the threads 10 are initially formed by, for example, acutting process, the cold roll wheel 14 may be used to cold work thethreads 10. Ideally, the end 16 of the wheel 14 will be positioned inthe threads 10 such that the end 16 is aligned with the root 18 of aparticular thread. Thereafter, force is applied to the cold roll wheel14 (by, for example, actuating one or more levers on the lathe) and thewheel 14 follows the path of the threads 10 thereby cold working thethreads 10 to improve the mechanical properties thereof.

However, in practice, it is very difficult to precisely locate the end16 of the cold roll wheel 14 at the desired location on the threadprofile. More specifically, in most thread rolling tools, the relativeposition of the end 16 of the cold roll wheel 14 relative to a holder(not shown) that is used to secure the cold roll tool to a machine toolis fixed. Thus, in using the existing thread rolling tools, a machinistmust expend great time and effort trying to insure that the end 16 ofthe wheel 14 is properly positioned in the root 18 of the thread 10.Such efforts may include the use of mirrors and additional lighting inan effort to insure that the end 16 is properly located in the root 18.Properly locating the end 16 in the root 18 of the thread is critical tothe cold working operation. Absent proper alignment, the cold workingprocess, where pressure on the order of, for example, approximately 1000psi or so is applied to the thread 10 via the wheel 14, may damage ordestroy the previously formed thread profiles. For example, a wheel 14(in dashed lines) that is misaligned with respect to the root 18 isdepicted in FIG. 1. If the end 16 of the misaligned wheel 14 is locatedat a position relatively far from the root 18 of the thread, applicationof pressure to the wheel 14 to cold work the threads may damage theexisting thread profile. At a minimum, the cold working process may notresult in the desired finished product if the end 16 of the wheel 14 isnot properly positioned in the threads 10. Moreover, the positioning ofprior art thread rolling tools is very time consuming, thereby limitingproductivity. Lastly, due to the difficult in properly aligning theprior art thread rolling tool described above, the chance of producingdefective end products is increased.

The present invention is directed to an apparatus and methods forsolving, or at least reducing the effects of, some or all of theaforementioned problems.

SUMMARY OF INVENTION

The present invention is directed to a thread rolling tool that may beused in forming various threads. In one illustrative embodiment, thetool comprises a tool holder, a boring bar and a cold roll wheeloperatively coupled to the boring bar, wherein a position of the coldroll wheel relative to the tool holder along a first direction ismoveable.

In another illustrative embodiment, the tool comprises a tool holder, aboring bar slidingly coupled to the tool holder to thereby allowmovement of the boring bar in a first direction relative to the toolholder, and a cold roll wheel operatively coupled to the boring bar.

In yet another illustrative embodiment, the tool comprises a toolholder, a boring bar that extends through and is slidingly coupled tothe tool holder to thereby allow movement of the boring bar in a firstdirection relative to the tool holder, a cold roll wheel operativelycoupled to the boring bar and at least one projection for limitingtravel of the boring bar relative to the tool holder along the firstdirection.

BRIEF DESCRIPTION OF DRAWINGS

The invention may be understood by reference to the followingdescription taken in conjunction with the accompanying drawings, inwhich like reference numerals identify like elements.

FIG. 1 is a schematic depiction of an illustrative thread profile in acold forming tool in accordance with prior art techniques.

FIG. 2 is a schematic depiction of an illustrative lathe having a threadrolling tool in accordance with one aspect of the present inventionpositioned therein.

FIGS. 3A-3C are various views of an illustrative thread rolling tool inaccordance with one embodiment of the present invention.

FIGS. 4A and 4B are views of one illustrative embodiment of the threadrolling tool during the assembly process.

FIGS. 5A and 5B are illustrative views of a thread rolling tool inaccordance with the present invention positioned in a lathe.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the description herein of specificembodiments is not intended to limit the invention to the particularforms disclosed, but on the contrary, the intention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION

Illustrative embodiments of the invention are described below. In theinterest of clarity, not all features of an actual implementation aredescribed in this specification. It will of course be appreciated thatin the development of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthis disclosure.

The present invention will now be described with reference to theattached figures. The words and phrases used herein should be understoodand interpreted to have a meaning consistent with the understanding ofthose words and phrases by those skilled in the relevant art. No specialdefinition of a term or phrase, i.e., a definition that is differentfrom the ordinary and customary meaning as understood by those skilledin the art, is intended to be implied by consistent usage of the term orphrase herein. To the extent that a term or phrase is intended to have aspecial meaning, i.e., a meaning other than that understood by skilledartisans, such a special definition will be expressly set forth in thespecification in a definitional manner that directly and unequivocallyprovides the special definition for the term or phrase.

In general, the present invention is directed to a thread rolling toolthat may be used in cold working threads. As will be recognized by thoseskilled in the art after a complete reading of the present application,the present invention may be employed with the formation of a variety ofdifferent types of threads on a variety of different type components.Thus, the present invention should not be considered as limited to theformation of any particular type of thread on any particular type ofcomponent unless such limitations are expressly set forth in theappended claims.

FIG. 2 is a schematic depiction of an illustrative lathe 20 having athread rolling tool 22 in accordance with one embodiment of the presentinvention positioned therein. The lathe 20 is provided by way of exampleonly and it should be understood to be representative of any of avariety of different types of lathes or other machinery used toinitially form a thread prior to performing a cold working process onthe thread, or a machine that is involved in any process of cold workingthreads. Thus, the present invention should not be considered as limitedin any respect as to the equipment or methodologies used in forming thethread unless such limitations are expressly set forth in the appendedclaims. As shown therein, the lathe 20 is comprised of a head stock 24,a chuck 26, a tool post 30, a bed 32, a cross slide lever 34, alongitudinal slide control 36 and a gear engagement lever 38. Alsodepicted in FIG. 2 is an illustrative workpiece 28, e.g., a section ofpipe. The thread rolling tool 22 is secured to the tool post 30 by aplurality of threaded pins 31.

FIGS. 3A and 3C are top and side views, respectively, of oneillustrative embodiment of the thread rolling tool 22 disclosed herein.FIG. 3B is an enlarged view of a portion of the thread rolling tool 22.As shown in these drawings, the thread rolling tool 22 is comprised of amoveable boring bar 42 that is slidingly coupled to a tool holder 40.That is, there is a sliding clearance between the tool holder 40 and themoveable boring bar 42 to allow the bar 42 to slide within the toolholder 40 in a first direction, as indicated by the double arrow 60,i.e., in a direction that is approximately parallel to the longitudinalaxis of the boring bar 42. In the depicted embodiment, the tool holder40 is comprised of a generally cylindrical body 41 and a clamp block 46that is of a generally rectangular shape. A key 44 is used to limitrelative movement between the moveable boring bar 42 and the tool holder40 in a second direction, i.e., to limit rotational movement between themoveable boring bar 42 and the tool holder 40 around the longitudinalaxis of the boring bar 42. Also, projections 48, i.e., screws, areprovided to limit relative longitudinal movement of the moveable boringbar 42 relative to the tool holder 40 in the first direction. In oneillustrative embodiment, the screws 48 are located in position so as tolimit the relative travel between the moveable boring bar 42 and thetool holder 40 along the first direction 60 to approximately 1-2 inches.Of course, the limit of this travel may be adjusted depending upon aparticular application. In the depicted embodiment, the clamp block 46has a generally rectangular configuration to facilitate securement ofthe thread rolling tool 22 to the tool post 30 on the lathe 20 via thethreaded pins 31. Of course, as will be recognized by those skilled inthe art, this particular configuration may be varied depending upon, forexample, the configuration of the machine that employs the threadrolling tool 22 of the present inventions. That is, other mechanisms maybe provided to insure that the thread rolling tool 22 may be secured toa machine, e.g., lathe 20, that may be employed in using the presentinvention.

The thread rolling tool 22 further comprises a cold roll wheel 50 havingan end 51, a piston 52, a dowel pin 54 that connects the wheel 50 to thepiston 52, a piston limit pin 56 that is used to limit the verticalmovement of the piston 52 and an O-ring 58 that provides the necessaryseal for hydraulic fluid employed in the present invention. The moveableboring bar 42 has an internal passageway 62 formed therein and apressure gauge 63 is coupled to the moveable boring bar 42. Thehydraulic fluid within the internal passageway 62 transmits the pressureacting on the wheel 50 to the pressure gauge 63. This pressure may beobserved by a machinist.

FIGS. 4A and 4B are various views depicting the assembly sequence of thethread rolling tool 22 in accordance with one embodiment of the presentinvention. As shown in FIG. 4A, a slot 66 is formed in the moveableboring bar 42 and a key 44 is positioned therein. The size andconfiguration of the key 44 and slot 66 may vary depending upon thedesired application. In one illustrative embodiment, the key 44 may beapproximately four inches in length (along the axial direction of themoveable boring bar 42) and its surface 44A may protrude above a surface42A of the moveable boring bar 42 by a distance of approximatelyone-half inch. A slot 68 is formed in the tool holder 40 and is adaptedto receive the key 44 positioned therein. The use of the key 44 limitsrelative movement of the moveable boring bar 42 and the tool holder 40in a given direction, i.e., the key 44 limits relative rotationalmovement between the tool holder 40 and the moveable boring bar 42. Asindicated in FIG. 4B, after the tool holder 40 is properly positionedover the key 44, protrusions, i.e., screws 48, may be secured in placeat the desired location to thereby limit the relative travel between themoveable boring bar 42 and the tool holder 40 in a first direction,e.g., in a longitudinal direction that is approximately parallel with alongitudinal axis of the moveable boring bar 42.

The operation and use of the thread rolling tool 22 of the presentinvention will now be described. At some point during the course ofassembly of the thread rolling tool 22, hydraulic fluid will beintroduced into the internal passageways 62 of the tool, via openingsprovided for the protrusions 48, e.g., screws, and/or the openingprovided to allow fluid communication with the pressure gauge 63.Typically, the screws 48 will be used as a means to fill and bleed offair within the internal passageway 62 and/or the piston 52 of the threadrolling tool 22. Once the system is properly filled with hydraulicfluid, it may be positioned on the tool post 30 as indicated in FIGS. 5Aand 5B. As shown therein, the thread rolling tool 22 is secured withinthe tool post 30 of the lathe 20 via a plurality of threaded pins 31.The threaded pins 31 engage the clamp block 46 on the tool holder 40. Ofcourse, as indicated before, the particular mechanism and manner bywhich the tool holder 40 is secured to the lathe 20, or any other typeof machinery, may vary depending upon the particular application.

Once the thread rolling tool 22 of the present invention is properlypositioned in the lathe 20, the machinist then advances the end 51 ofthe cold roll wheel 50 to a point where it is proximate a previouslyformed thread profile. By incremental actuation of various controllevers on the lathe 20 and/or movement of the moveable boring bar 42,the end 51 of the cold roll wheel 50 may be brought into engagement withpreviously formed threads on the workpiece 28. Due to the fact that thethread rolling tool 22 of the present invention allows relativemovement, e.g., in a longitudinal direction, between the cold roll wheel50 and the tool holder 40, the end 51 of the wheel 50 can move (in alateral direction) so that it may tend to naturally find the properposition within the thread profile, i.e., the end 51 may be positionedat the root of the thread prior to beginning cold working operations.Moreover, as the lathe is actuated to apply pressure to the end 51 ofthe wheel 50, the self-alignment forces tend to become greater, i.e.,the end 51 would tend to be biased toward the root of a particularthread profile due to the various tapered surfaces.

Through use of the present invention, the end 51 of the cold roll wheel50 may be more quickly and properly positioned at the desired locationprior to beginning cold working operations. Due to the allowed relativelongitudinal movement between the cold roll wheel 50 and the tool holder40, the present invention enables a machinist to readily locate andposition the end 51 of the cold roll wheel 50 at the desired location.In turn, this improves manufacturing inefficiencies and leads to reducedwaste.

The present invention is directed to a thread rolling tool that may beused in forming various threads. In one illustrative embodiment, thetool comprises a tool holder, a boring bar and a cold roll wheeloperatively coupled to the boring bar, wherein a position of the coldroll wheel relative to the tool holder along a first direction ismoveable.

In another illustrative embodiment, the tool comprises a tool holder, aboring bar slidingly coupled to the tool holder to thereby allowmovement of the boring bar in a first direction relative to the toolholder, and a cold roll wheel operatively coupled to the boring bar.

In yet another illustrative embodiment, the tool comprises a toolholder, a boring bar that extends through and is slidingly coupled tothe tool holder to thereby allow movement of the boring bar in a firstdirection relative to the tool holder, a cold roll wheel operativelycoupled to the boring bar and at least one projection for limitingtravel of the boring bar relative to the tool holder along the firstdirection.

The particular embodiments disclosed above are illustrative only, as theinvention may be modified and practiced in different but equivalentmanners apparent to those skilled in the art having the benefit of theteachings herein. For example, the process steps set forth above may beperformed in a different order. Furthermore, no limitations are intendedto the details of construction or design herein shown, other than asdescribed in the claims below. It is therefore evident that theparticular embodiments disclosed above may be altered or modified andall such variations are considered within the scope and spirit of theinvention. Accordingly, the protection sought herein is as set forth inthe claims below.

1. A thread rolling tool, comprising: a tool holder; a boring bar; and acold roll wheel operatively coupled to said boring bar, wherein aposition of said cold roll wheel relative to said tool holder along afirst direction is moveable.
 2. The thread rolling tool of claim 1,further comprising means for limiting movement of said cold roll wheelrelative to said tool holder along said first direction.
 3. The threadrolling tool of claim 1, further comprising means for limiting movementof said cold roll wheel relative to said tool holder in a seconddirection.
 4. The thread rolling tool of claim 1, further comprising: apiston operatively coupled to said cold roll wheel; and a pressure gaugefor determining a pressure applied by said cold roll wheel.
 5. A threadrolling tool, comprising: a tool holder; a boring bar slidingly coupledto said tool holder to thereby allow movement of said boring bar in afirst direction relative to said tool holder; and a cold roll wheeloperatively coupled to said boring bar.
 6. The thread rolling tool ofclaim 5, further comprising at least one projection for limiting travelof said boring bar relative to said tool holder along said firstdirection.
 7. The thread rolling tool of claim 5, wherein said boringbar extends through said tool holder and is coupled thereto by a key. 8.The thread rolling tool of claim 7, wherein said key is positioned in afirst slot formed in said boring bar and a second slot formed in saidtool holder.
 9. The thread rolling tool of claim 5, further comprising akey that couples said boring bar to said tool holder to thereby limitmovement of said boring bar relative to said tool holder in a seconddirection.
 10. The thread rolling tool of claim 5, wherein said toolholder comprises a generally cylindrical section and a rectangular clampblock coupled to said cylindrical section.
 11. The thread rolling toolof claim 5, further comprising: a piston operatively coupled to saidcold roll wheel; a pressure gauge; and an internal passageway formed insaid boring bar, said internal passageway adapted to be filled with ahydraulic fluid.
 12. A thread rolling tool, comprising: a tool holder; aboring bar that extends through and is slidingly coupled to said toolholder to thereby allow movement of said boring bar in a first directionrelative to said tool holder; a cold roll wheel operatively coupled tosaid boring bar; and at least one projection for limiting travel of saidboring bar relative to said tool holder along said first direction. 13.The thread rolling tool of claim 12, further comprising a key thatcouples said boring bar to said tool holder to thereby limit movement ofsaid boring bar relative to said tool holder in a second direction. 14.The thread rolling tool of claim 12, wherein said tool holder comprisesa generally cylindrical section and a rectangular clamp block coupled tosaid cylindrical section.
 15. The thread rolling tool of claim 12,further comprising: a piston operatively coupled to said cold rollwheel; a pressure gauge; and an internal passageway formed in saidboring bar, said internal passageway adapted to be filled with ahydraulic fluid.
 16. A thread rolling tool, comprising: a tool holder; aboring bar that extends through and is slidingly coupled to said toolholder to thereby allow movement of said boring bar in a first directionrelative to said tool holder; a cold roll wheel operatively coupled tosaid boring bar; at least two projections for limiting travel of saidboring bar relative to said tool holder along said first direction; anda key that couples said boring bar to said tool holder to thereby limitmovement of said boring bar relative to said tool holder in a seconddirection.
 17. The thread rolling tool of claim 16, wherein said toolholder comprises a generally cylindrical section and a rectangular clampblock coupled to said cylindrical section.
 18. The thread rolling toolof claim 16, further comprising: a piston operatively coupled to saidcold roll wheel; a pressure gauge; and an internal passageway formed insaid boring bar, said internal passageway adapted to be filled with ahydraulic fluid.